In the structure of a corrugated board known from U.S. Pat. No. 4,685,563, a full-area continuous shielding layer of uniform thickness is provided in the interior of the structure. The outer surfaces of the corrugated board are untreated and free, respectively.
In the structure of a corrugated board known from U.S. Pat. No. 4,482,048, at least one shielding, full-area layer is provided, again in the interior of the structure. The outer surfaces of the corrugated board are untreated.
In the case of a folding case consisting of corrugated board, which is known from DE-B1-2 947 262, at least the free side of the cover layer facing the interior has been printed on with an aqueous emulsion having carbon particles dispersed therein.
DE-A-3 214 940 discloses a sheeting material which has been printed on with a network or latticework of intersecting lines of conductive printing colour on one side thereof or on both sides thereof. When kraft paper is used as a sheeting material for the outer cover layer of a corrugated board, the network is only printed on the outer surface thereof; the sheeting material is transparent; in the case of corrugated board, openings are provided which permit looking through.
A full-area, uniform application of the shield means does not only necessitate a comparatively large amount and an unnecessarily large amount of shielding material, but, due to the shield means integrated in the interior of the corrugated board structure, major problems may arise when the layers are glued together as well as with respect to the durability of the glued connection. A corrugated board which has been treated in this way is difficult to dispose of. A network printed as a shield means onto the outer surface of a sheeting material is susceptible to damage and permits in its interspaces the transmission of charges or discharges to corners, edges or tips located in these interspaces and belonging to the components to be protected.